Meeting Abstract
Although trade-offs are a key component of life-history theory we still know relatively little about the specific physiological mechanisms underlying any trade-off. Much attention has focussed on the trade-off between reproduction and immune function and although it is widely assumed that the limiting resource for this trade-off is energy there is only weak and contradictory evidence that variation in immune function is driven by energy or resource costs of reproduction per se (or vice versa). Moreover, any trade-off between immune function and reproduction will not only be driven by the female (parent) but also by her offspring, when both reproductive (e.g. yolk hormones) and immune (e.g. maternal antibodies, MAb) resources are transferred to eggs. Here we studied the effects of mounting a secondary immune response (against injections of LPS spaced 10 days apart) on reproductive investment of female zebra finches (Taeniopygia guttata). We obtained data on laying interval, egg mass and clutch size of LPS-treated and control females (pre- and post-LPS injection) and blood sampled females to measure Ab titers. We then manipulated eggs with high- and low-MAb by egg injection to elevate yolk T. We were therefore able to investigate a) the effect of mounting an immune response on the female’s own reproductive investment, and b) the consequences of the female’s reproductive decisions for offspring fitness in terms of egg mass, maternally-transferred Ab (which we predicted would enhance offspring immune function), and maternally-derived T (which we predicted would enhance offspring growth). We expected that the trade-off between effects of MAb and yolk T in offspring would interact with the trade-off between immune function and reproduction in females.
